CHEMICAL ANALYSIS OF URINARY TRACT CALCULI BY DUAL …

International Journal of Medical Science and Education pISSN- 2348 4438 eISSN-2349- 3208

Published by Association for Scientific and Medical

Education (ASME) 89

Vol.3; Issue: 2;April-June 2016

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CHEMICAL ANALYSIS OF URINARY TRACT CALCULI BY DUAL SOURCE CT IN

ARAVALI HILLY AREA

Dr. Dwarka Prasad Agarwal1 , Dr. Kapil Vyas

2*

1.2 Associate Professor, Department of Radio-diagnosis, Pacific Medical College and Hospital, Udaipur.

*Email id of corresponding author- [email protected]

Received: 15/12/2015 Revised: 11/04/2016 Accepted: 21/04/2016

ABSTRACT:

Objective: To qualitatively analyze the uroliths in vivo using dual source CT by crystallography as the

reference standard in Udaipur, an Aravalli Hilly area located in southern region of Rajasthan (India) so as

to evaluate the predominant constituent present in them and report its significance. Materials and

Methods: The study was conducted in Radiology department of Pacific Medical College & hospital,

Udaipur on 25 patients of all age group (4 to 70 years) with clinical suspicion or known/ suspected calculi

on X-ray or USG. The 128 slice Somatom definition dual source CT was used to analyse chemical

composition of renal, ureteric and vesicle stones. Results: Of the 25 patients studied, 13 were males and

12 females. 22 patients (88%) had oxalate stones, 2(8%) had uric acid stones and 1(4%) had mixed

calculus of oxalate and hydroxyapatite. There were total 48 calculi of which 30 were in kidneys (62.5%),

14 in ureters (29.2%) and 4 in urinary bladder (8.3%) of these 25 patients. 12 patients had single calculus

and 13 had multiple calculi. The CT density for calcium oxalate stones was around & more than 1000

HU, for uric acid stones around 500 HU to 600 HU and for the mixed stone 876 HU. Conclusion: The

study reveals significantly high incidence of calcium oxalate stones in Aravali hilly areas which may be

due to altered eating and drinking habits which promoted its formation in these individuals. The MDCT

without dual source was accurate in classifying urinary stone composition. Randomized clinical trials

should be encouraged for validating this technique on large populations.This may help the health care

providers to look through the risk factors for calculi formation in this area which might enable them to

plan therapies and prevent recurrence of stone formation.

Key Words: Urolithiasis, dual source CT, chemical composition.

INTRODUCTION:

Urinary stones (Urolithiasis) are the consequence

of crystallization and aggregation of highly

concentrated urinary components. It is a common

reason of outpatient visits and hospitalization.

Moreover, the risk of its recurrence even after

treatment is about 50% in 10 years (1). The

clinical presentation could be an occasional

abdominal pain or even renal failure which is

independent of the stone size (2).

The epidemiology of urolithiasis differs in

Original research article

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accordance with the geographical area which is

on account of difference in race, diet and

climatic factors. Furthermore changing socio-

economic conditions affects lithiasis in terms of

both the site and the chemical-physical

composition of the calculi.

Urolithiasis as a multifactorial disease which is

distributed worldwide in urban, rural, non

industrial and industrial regions with different

chemical composition of analyzed stones in

context to etiological and risk factors. The

majority (75–85%) of stones are made of

calcium, but 2–15% are struvite, while uric acid

stones account for 6–10% and cystine stones 1–

2%. In USA the most common stone

composition is calcium oxalate (40–60%),

followed by uric acid (5–10%), hydroxyapatite

(2–4%), and cystine (1–3%) (1). The most

common type of kidney stone seen in the UK is

calcium-containing – usually calcium oxalate or

a mixture of calcium oxalate and calcium

phosphate (3).

In India calcium oxalate is the most common

stone and much more frequent than USA and

European countries, particularly in Aravali hilly

tribal areas, where there is poor population and

poor resources. Most of the people there are still

dependent on the hard ground water for the

drinking use so the incidence of calcium oxalate

stones is significantly high. The ideal level of

hardness should be 50-150mg/L. Softening of

water is recommended when hardness exceeds

3mEq/L (300mgper liter) (4).

The MDCT without dual source is more precise

than IVU for detection of urinary tract stones as

it can give information of even a millimeter sized

calculus, but effort made to chemically analyse

the stone only on the basis of density do not give

appreciable results (5). The dual energy

acquisition with syngo CT DE Calculi

Characterization software allowed not only a

precise localization of stones but also gave more

accurate information of its chemical composition

which is helpful in choice of approach of

treatment (6). Dual source CT is a new

technology that employs two different x-ray

sources that provide an image resolution that has

not been possible with conventional single

source CT (7).

The present study was aimed to qualitatively

analyze the uroliths in vivo using dual source CT

by crystallography as the reference standard in

Udaipur, an Aravalli Hilly area located in

southern region of Rajasthan (India) so as to

evaluate the predominant constituent present in

them and report its significance.

MATERIALS AND METHODS

The study was conducted in Radiology

department of Pacific Medical College &

hospital, Udaipur, which covered the population

of adjacent hilly areas.

Twenty five patients of all age group (4 to 70

years) with clinical suspicion or known/

suspected calculi on X-ray or USG were

included for study. Out of 25 patients, 13

patients were male and 12 patients were females.

Informed consent was obtained from the patients

after the institutional ethical clearance for the

study.

The 128 slice Somatom definition dual source

CT by siemens at our institution is capable of





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analysing chemical composition of renal, ureteric

and vesicle stones by syngo CT DE Calculi

Characterization software with almost same

accuracy with actual chemical analysis by

crystallography. Knowledge about chemical

composition guides the choice of appropriate

treatment approach.

All patients underwent plain CT KUB for urinary

tract evaluation using a dual-energy technique

with parameters for tube 1 (MAS=85; voltage

140 KV) and for tube 2 (MAS= 468; voltage 80

KV). The pitch for the study was 0.7 with 5mm

slice thickness which reconstructed at 1.5mm.

3D reconstruction was done for each study.

Acquisition was 14 x 1.2 mm and rotation time

0.5sec. The images were post processed on

dedicated syngo via remote work station with DE

Calculi Characterization software.

Average attenuation values in Hounsfield units

were calculated for the two energy levels, and

the ratio between the average low-energy

attenuation and the average high-energy

attenuation was derived, then this ratio for each

stone was projected on a graph of four stone

types (calcium oxalate, hydroxyapatite, cystine

and uric acid) where lower part contains non

calcium stones (hydroxyapatite, cystine, and uric

acid) with lower most line refers to uric acid

stones and upper part contains calcium stones

(calcium oxalate). If density and attenuation

ratios of calculus lies in upper part of graph the

calculus is automatically painted blue and if

density and attenuation ratios of calculus lies in

lower part of graph the calculus is painted red.

Determination of calculus composition can be

made according to the position of calculus on

graph in relation to the values of calcium oxalate,

hydroxyapatite, cystine, and uric acid calculi.

RESULTS

A total of 25 patients were studied of which 13

were males and 12 females. Out of 25 patients,

22 patients (88%) had oxalate stones, 2 patients

(8%) had uric acid stones and 1 patient (4%) had

mixed calculus of oxalate and hydroxyapatite.

There were total 48 calculi in kidneys, bladder

and ureters of 25 patients. 12 patients had single

calculus and 13 had multiple calculi. Out of 48

calculi, the percentage of distribution with

respect to location was as-30 calculi were in

kidneys (62.5%), 14 in ureters (29.2%) and 4 in

urinary bladder (8.3%). One calculus in right

kidney was Staghorn calculus. Percentage was

calculated according total number of stones

which showed that oxalate stones were 93.75%,

uric acid stones 4.17% and mixed stone were

2.08%.On analysis, only two calculi were found

to be formed by uric acid composition and one

was found formed by mixed oxalate and

hydroxyapatite composition. Rest 45 calculi were

formed by calcium oxalate. Stone diameter

varied from 2 mm to 28 mm sized (two < 2mm

sized calculi were discarded from study, as FOI

cannot be selected for Calculi Characterization).

The CT density for calcium oxalate stones was

around & more than 1000 HU, for uric acid

stones around 500 HU to 600 HU and for the

mixed stone 876 HU.

Along with chemical composition of stone we

also observed the site, size and CT density of the

stones.





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Fig.1 Shows Above images are elaborated with Calculi characterization software by siemens, including

three views of stone in sagittal, axial planes and 3D in coronal plane with graphic presentation. In

diagram, graphs of four stone types (calcium oxalate, hydroxyapatite, cystine, and uric acid) are described

by four small circles According to their increased attenuation ratios (CT density at 140 kVp on x-axis and

CT density at 80 kVp on y-axis).. Lower part contains noncalcium stones (hydroxyapatite, cystine, and

uric acid) with lower most line refers to uric acid stones and upper part contains calcium stones (calcium

oxalate). This is the case of 50 year old male having a calculus of 11mm sizes in the right renal pelvis.

The calculus shown in three views is automatically painted blue by software as its CT density lies in

upper part of graph (in graph the circle of calculus KS1 showing density of around 2000 and average

attenuation ratio 1.5, lying upper most part of graph). These software findings are suggestive of calcium

oxalate calculus.

DISCUSSION

Level of hardness of water varies from place to

place in this Aravali region but was found to be

higher than the acceptable level. In a study

conducted by B.K. Sharma and L.L. Sharma

(2008) the hardness of water in Udaipur district

was reported to be 150-500 mg/L, in Banswara

274-276 mg/L, and in Dungarpur 270-290 mg/L

(8).

Most of the regions of the area we studied the

subjects from also had high fluoride. The

prevalence of urolithiasis was 4.6 times higher in

EA than in NEA. Furthermore, the prevalence

was almost double in subjects with fluorosis than

without fluorosis in the endemic area (9, 10).

High and progressively increasing incidence of

urolithiasis in Udaipur and some other parts of

Rajasthan have been reported by Pendse et al

(11).





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Urolithiasis can be found in any part of the

urinary system of either sexes. Our study

reported a predominance suffered by males,

located mostly in the kidneys, with mostly

oxalate as the chemical composition. The types

of stones formed depend mainly on the

composition of urine, which in turn is governed

by the kind of diet consumed in the areas. Our

study was in tune with Ansari et al who analysed

1050 stones (900 renal, 150 ureteric) and found

977 (93%) were composed of calcium oxalate.

Only small percentage contain of uric acid

10.95%) struvite 1.4% apatite 1.8%.

It is important to know the chemical composition

of stones so as to be able to plan therapies and

prevent recurrences. The risk of recurrence for

calcium oxalate stones is 10% after an year and

50% at 10 years after treatment (8). These

therapies might eliminate the need for

extracorporeal shock wave lithotripsy, a

procedure that is expensive and subject to

complications (12,13,14).

CONCLUSION

The study reveals significantly high incidence of

calcium oxalate stones (88% of all patients and

93.75% stones of total kinds of stones) in Aravali

hilly areas which may be due to altered eating

and drinking habits which promoted it’s

formation in these individuals. The MDCT

without dual source was accurate in classifying

urinary stone composition. Randomized clinical

trials should be encouraged for validating this

technique on large populations. The collected

information in this regard may help to look

through the risk factors for calculi formation in

this area which might enable the health care

providers for deciding surgical / non surgical

approach for treatment and also will help them to

decide strategy for prevention of recurrence of

stone formation in them.

REFERENCES

1. Moe OW. Kidney stones:

pathophysiology and medical

management. Lancet 2006; 367:333–344.

2. British journal of renal medicine. 2013;

18 (1):16.

3. Ajayi L, Jaeger P, Robertson W, et al.

Renal stone disease. Medicine 2007; 35:

415-419.

4. K. Park. Preventive and social medicine

18th edition, enviorment and health; pp

538.

5. Stacul F, Rossi A, Cova MA. CT

urography: the end of IVU? Radiol Med

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6. Graser A, Johnson TRC, Bader M, et al.

Dual energy CT characterization of

urinart calculi: initial in vitro and clinical

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7. Brian R. Matlaga, Satomi Kawamoto,

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8. B.K. Sharma, L.L. Sharma. Assessment

of Hand Pump Waters in Three Tribal

Dominated District. J Environ Sci

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https://www.ncbi.nlm.nih.gov/pubmed/19295097

https://www.ncbi.nlm.nih.gov/pubmed/19295097





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10. Singh PP, Barjatiya MK, Dhing S,

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Udaipur (western part of India.

Urological Research. 1986; 14 (2): 59-62.

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basis for urolithiasis. Surgery 2008;

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Fig.2 This is the case of 55 year old male having a staghorn calculus of 26mm size in the right renal pelvis

with 6 small calculus in right inferior calyces and one calculus of 8mm sized in middle calyx of left

kidney along with left upper ureteric calculus of 17mm size and resultant left hydroureteronephrosis. The

ureteric calculus shown in three views is automatically painted blue by software as its CT density lies in

upper part of graph (in graph the circle of calculus KS3 showing density of around 1100 and average

attenuation ratio 1.5, lying upper most part of graph). These software findings are suggestive of calcium

oxalate calculus.





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Fig.3 Elaborated images with calculi characterization software by siemens, including three views of stone

in sagittal, axial planes and 3D in coronal plane with graphic presentation. This is the case of 4 year

female child having a large urinary bladder calculus of 29mm with average CT density of 527 HU. The

calculus in three views is automatically painted red by software as its CT density and attenuation ratios

lies in lower part of graph. These software findings are suggestive of uric acid stone.

CHEMICAL ANALYSIS OF URINARY TRACT CALCULI BY DUAL …

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